Simultaneity of Events: Is It Possible?

In summary, the conversation discusses the hypothetical concept of traveling through a wormhole to a planet near Alpha Centauri and sending a signal back to Earth, only to receive it 26 years later. There is a debate over whether this is possible or not, with one person arguing that it would require traveling backwards in time and the other person explaining that it is not going back in time, but rather arriving in the past. The conversation also touches on the idea of close time-like curves and the self-consistency principle.
  • #1
proculation
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Hi,

A friend of mine asked me something about relativistic physics. It's all hypothetical and I told him it's a paradox that cannot be achieved since you cannot go back in time.

Here's his assumption:

Let's say that you pass through a 'wormhole' to a planet near Alpha Centauri (26 lightyears). You send a signal to Earth and then you get back into your 'ship' from another worm hole.

From your point of view, it took you about 5 minutes to do all that. You are back on Earth 5 minutes after.

26 years later, you receive the signal you sent from Alpha Centauri. That would mean you are on Earth to receive the signal and also on the planet of Alpha Centauri.

My guess is that it is impossible since when you would get back to Earth, you would be traveling backwards in time.

Am I right ?

Oiivier
 
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  • #2
Wormholes can create close time-like curves.
The same problem exists inside rotating black holes

CTL curve itself is not a contradisction per se, wiki for example novikov self-consistency principle.
 
  • #3
That's exactly what I think. it's impossible.

You can't go back in time to receive the signal.
 
  • #4
You don't 'go back in time', you always go forward, but arrive to the past. Like on the globe: you can always go west, but return to the East
 
  • #5
Dmitry67 said:
You don't 'go back in time', you always go forward, but arrive to the past. Like on the globe: you can always go west, but return to the East

That's my understanding.
 
  • #6
I don't see how receiving the signal means you are on Alpha Centauri.

It's like I will send you a letter, meanwhile go on a trip around the world, but when you'll receive the letter it will require me to be home.

Maybe I didn't get your question right.
 
  • #7
That's in a Newtonian world. But in a Einstein world... It can't happen.

elibj123 said:
I don't see how receiving the signal means you are on Alpha Centauri.

It's like I will send you a letter, meanwhile go on a trip around the world, but when you'll receive the letter it will require me to be home.

Maybe I didn't get your question right.
 

1. What is simultaneity of events?

Simultaneity of events refers to the occurrence of two or more events at the same time or instant.

2. Is it possible for two events to happen simultaneously?

The concept of simultaneity is relative and can vary depending on the observer's frame of reference. In some cases, two events may appear to happen at the same time, while in others, they may not.

3. How is simultaneity of events measured?

In physics, simultaneity is measured using coordinates and time intervals in a specific frame of reference. This can be done through techniques such as time dilation and the theory of relativity.

4. Can simultaneity be proven or is it just a theory?

The concept of simultaneity is a fundamental aspect of physics and has been extensively studied and tested through experiments and observations. While it cannot be proven in an absolute sense, it has been proven to hold true in many scenarios.

5. Does the speed of light affect the simultaneity of events?

According to the theory of relativity, the speed of light is constant and is the same for all observers. This means that the speed of light does not affect the simultaneity of events, as it is a fundamental constant in determining the relationship between space and time.

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